The Effect of Chemical Composition of Aggregate on the Performance of Hot and Warm Mix Asphalt in Presence of Water

Abstract

Warm mix asphalt (WMA) is a new technology designed to lower the energy required for asphalt mixture production and to reduce the amount of undesirable odors emitted during the mixing and paving processes. The Warm Asphalt Mix-foam (WAM-Foam) type of WMA is applied in two stages of the mixing process. The first stage is to coat the surface of the aggregate with a soft asphalt binder. Then a foamed hard binder is introduced to the mixture to decrease the mix temperature. This technology can reduce the energy consumption up to 30%. The main objectives of this study were to investigate the chemical and mineralogical compositions of aggregate across the state of Ohio and to assess the performance of WMA foamed asphalt specimens collected in two different locations in Ohio and compare the results with the performance of hot mix asphalt (HMA) specimens in presence of water by using a dynamic modulus test (E*) and asphalt concrete cracking device (ACCD). The aggregate gradation for both projects was almost the same. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that the Columbus project mixture contained more silica (SiO2) than the Woodville project mixture. Based on the results obtained from the ACCD, the HMA and WMA from Columbus had a higher strain than the HMA and WMA from Woodville. For each location, the strength of the HMA was higher than the strength of WMA. The dynamic modulus confirmed the stiffness difference, and indicated it may be caused by Ohio's foaming process trapping more water within the aggregate-binder interface.